Publication Date
5-2025
Date of Final Oral Examination (Defense)
2-27-2025
Type of Culminating Activity
Thesis
Degree Title
Master of Public Health
Department
Community and Environmental Health
Supervisory Committee Chair
Douglas Myers, Sc.D.
Supervisory Committee Co-Chair
Vinita Sharma, Ph.D., MPH, CPH, CHES
Supervisory Committee Member
Bozena Morawski, MPH, Ph.D.
Abstract
Background: Oncotype DX RS is a 21-gene assay that can be used to guide treatment decisions regarding adjuvant chemotherapy for women diagnosed with early-stage, estrogen receptor positive, human epidermal growth factor negative (ER+/HER2-) breast cancer. Despite extensive clinical validation and inclusion in multiple clinical guidelines, research suggests that Oncotype DX RS may be underutilized in the United States. Oncotype DX RS testing has not been evaluated in Idaho.
Objective: This study quantified geographic and sociodemographic variability and temporal trends in Oncotype DX RS testing in Idaho.
Methods: A population-level secondary data analysis was conducted with data from the Cancer Data Registry of Idaho. We included early-stage (0–3 positive lymph nodes) ER+/HER2- breast cancers diagnosed among female Idahoans during 2013–2019. Multivariable and multilevel logistic regression were used to quantify associations between linkage to Oncotype DX RS testing and rural versus urban residency while adjusting for age, year of diagnosis, summary stage, race, ethnicity, tumor size, insurance type, and nodal status. County of patient residency was included as a random effect in multilevel models.
Results: Out of 5,031 eligible tumors, 43% (N = 2,162) were linked to Oncotype DX RS testing. Linkage to testing increased from 37% in 2013 to 46% in 2019. Multilevel logistic regression results showed residential location was not significantly associated with testing linkage status (OR 0.97, 95% CI: 0.72–1.31, p = 0.86) after adjusting for county-level clustering and other covariates, indicating that the individual effect of residential location on testing status was masked by variability at the county level. Increasing age (OR 0.95, 95% CI: 0.95-0.96, p < 0.001), being uninsured (or having unknown insurance status) (OR 0.59, 95% CI: 0.38-0.90, p = 0.02), and being insured through Medicaid (OR 0.66, 95% CI: 0.52-0.84, p < 0.001) were associated with significantly lower odds of being linked to Oncotype DX RS testing in multivariable models.
Conclusion: While testing linkage for Oncotype DX RS increased over the study period, further research on access to care as well as patient and provider level factors affecting clinical decision-making for early-stage breast cancer is warranted to inform future public health research.
DOI
https://doi.org/10.18122/td.2346.boisestate
Recommended Citation
Buster, Jessica, "Assessing Genomic Testing Variability Among Female Breast Cancer Patients in the State of Idaho" (2025). Boise State University Theses and Dissertations. 2346.
https://doi.org/10.18122/td.2346.boisestate